Dr. Rebecca Bigler, director of The University of Texas at Austin’s Gender and Racial Attitudes Lab, has done a number of experiments with preschoolers and colored T-shirts.  In one, she took a classroom of 4 and 5 year olds and put half in red T shirts and the other half in blue T shirts .  The children wore these colored T shirts for three weeks but teachers were instructed not to notice or mention the colors in any way.  At the end of the three weeks, children were asked to evaluate the skill, abilities, characteristics, and intelligence of each group.